Core and coil assembly

ABSTRACT

A shell core transformer having a core and coil assembly located in a casing with each coil being a separate element having a plurality of windings of conductor encapsulated in a potting compound. The coils are assembled in side-by-side relation and embraced by a magnetizable material preferably in the form of ribbon bands spirally wound around two or all four legs of the rectangularly shaped coils. Posts are formed integral with the encapsulant which serve as terminals and mounting members supporting the core and coil assembly within the casing. Each coil has a semiconductive film on the surface of the encapsulant. To facilitate dissipating heat, heat sinks are provided consisting of flat plates or fins having a portion disposed between adjacent faces of the coils and a further portion projecting radially outward therefrom and in contact with the casing. The casing also is provided, in some instances, with fins. There is also a method of forming a coil which includes winding a plurality of turns onto a disc having a groove in one face thereof for receiving the conductor and subsequently assembling further members to enclose the wound coil in a chamber for receiving an encapsulant.

United States Patent [72] Inventors Anthony B. Trench 25 Elizabeth St.,Thornhill;

Vaughan 1. C. Marks, 56 Blakemanor Blvd., Scarborough, both of Canada[21] Appl. No. 814,733 [22] Filed Apr. 9, 1969 [45] Patented Nov. 2,1971 [32] Priority Apr. 11, 1968 [33] Canada [31] 017327 [54] CORE ANDCOIL ASSEMBLY 7 Claims, 14 Drawing Figs.

[52] U.S. C1 336/61, 336/84, 336/92, 336/96, 336/107, 336/205 [51] Int.Cl. 11011 27/06 [50] Field of Search 336/61,9 2, 84,96, 205, 105, 107

[56] References Cited UNITED STATES PATENTS 2,997,527 8/1961 Kessel etal. 336/96 X 3,246,272 4/1966 Wiley 336/96 X 3,354,417 11/1967 Davis336/96X 1,367,957 2/1921 Garretson 336/92 1,659,548 2/1928 Johannesen...336/92 2,185,831 1/1940 Camilli 336/96 2,613,238 10/1952 Wiesemam.336/84 X 2,652,521 9/1953 Westphal 336/84 Primary Examiner-Thomas J.Kozma Attorney-Shanley and O'Neil ABSTRACT: A shell core transformerhaving a core and coil assembly located in a casing with each coil beinga separate element having a plurality of windings of conductorencapsulated in a potting compound. The coils are assembled insideby-side relation and embraced by a ma'gnetizable material preferablyin the form of ribbon bands spirally wound around two or all four legsof the rectangularly shaped coils. Posts are formed integral with theencapsulant which serve as terminals and mounting members supporting thecore and coil assembly within the casing. Each coil has a semiconductivefilm on the surface of the encapsulant. To facilitate dissipating heat,heat sinks are provided consisting of flat plates or fins having aportion disposed between adjacent faces of the coils and a furtherportion projecting radially outward therefrom and in contact with thecasing. The casing also is provided, in some instances, with fins. Thereis also a method of forming a coil which includes winding a plurality ofturns onto a disc having a groove in one face thereof for receiving theconductor and subsequently assembling further members to enclose thewound coil in a chamber for receiving an encapsulant.

PATENTED nuvz I971 SHEET 1 BF 4 PATENTEU NUV2 1911 SHEET 3 BF 4 CGRE ANDCOIL ASSEMBLY The present invention relates to an insulated coilencapsulated in a potting compound, to an encapsulated coil having ametallized coating on the surface thereof, to a transformer consistingof a plurality of individual coils disposed side-byside and each ofwhich consists of 'a plurality of turns of con ductor encapsulated in apotting compound, and to a transfonner wherein at least one of the coilsis covered by a metallized coating on the surface thereof.

It is an object of the present invention to provide a coil which may beused along with one or more similar coils to form an induction device.

A further object of the present invention is to provide a transformer ofindividual discrete coil elements which may be readily removed andreplaced.

A still further object of the present invention is to provide a methodof making a transformer whereby transformers of various capacities maybe manufactured from appropriate selection of standard coil assemblies.

In accordance with one aspect of the present invention, there isprovided a coil for use in an induction device comprising a plurality ofturns of conductor encapsulated in a potting compound and a metallizedfilm coating on the external surface of the encapsulant.

In accordance with a further aspect of the present invention, thereisprovided a coil for a transformer comprising at least two coil elementsdisposed side-by-side adjacent one another and each coil elementcomprising a plurality of turns of conductor encapsulated in a pottingcompound and having a metallized film on the external surface thereof.

In accordance with a further aspect of the present invention, there isprovided a transformer comprising a plurality of individual discretecoils disposed side by-side in close adjacent relation and at least onebody of magnetizable material embracing a selected portion of theassembled coils, said coils each consisting of a plurality of turns ofconductor encapsulated in a potting compound.

The invention is illustrated, by way of example, in the accompanyingdrawings wherein:

FIG. I is a partial sectional, top plan view of a transformerconstructed in accordance with the present invention;

FIG. 2 is a cross-sectional view taken substantially along the line 2-2ofFIG. I;

FIG. 3 is a partial section, oblique view of a portion of a transformerillustrating a modified casing;

FIG. 4 is a cross-sectional view of the casing illustrated in FIG. 3,taken substantially along line 44;

FIG. 5 is an elevational view of a portion of a core and coil assemblyfor an induction device;

FIG. 6 is a section taken along section 6-6 of FIG. 5; FIG. 7 is asectional view taken along section 7-7 of FIG.

FIG. 8 is a side elevational view of the assembly illustrated in FIG. 5;

FIG. 9 is a section similar to FIG. 6;

FIG. I0 is a top plan view of a portion of one terminal and bushing forthe coil assembly;

FIG. 11 is a partial cross-sectional view of one terminal and bushingfor the coil assembly;

FIG. 12 is an oblique view, in partial section, of a form for use inmaking a coil and encapsulating the same;

FIG. 13 is a diagrammatic illustration of one method of making a coil;and

FIG. 14 is a diagrammatic illustration of apparatus for encapsulating acoil.

Referring now in detail to the drawings. there is illustrated in FIGS. 1and 2 a transformer consisting of a casing enclosing a core and coilassembly 50 and a plurality of heat sinks 70 which engage the core andcoil assembly and the casmg.

The casing 20 consists of respective front and rear panels 21 and 22each appropriately formed to provide a side wall and a portion of an endwall. Each panel includes, at opposed marginal edges, an outwardlydirected flange 23 substantially parallel to and offset from the mainportion of the panel. A pair of flanges 23 on panel 21 are attached tothe correspondingly oriented flanges 23 on the panel 22 by means ofbolts,- welding or the like and thereby provide a space between the sidefaces to receive the core and coil assembly. A cover member 24 overliesthe panel members 21 and 22 except for the outwardly directed flanges 23and, if desired, a downwardly turned lip may overlap a selected upperportion of the side walls. The core and coil assembly 50 may besuspended from the cover 24. Alternatively, the core and coil assemblymay be supported upon a bottom wall 25 secured to the casing panelmembers 21 and 22 as, for example, by welding, riveting, or the like.The cover member 24 and the bottom wall 25 have respective high-voltagebushings 26 and low-volt age bushings 27 projecting therethrough andarranged in a manner to be described in more detail hereinafter.

In FIGS. 3 and 4, there is illustrated a transformer 10A consisting of amodified casing 30 and a core and coil assembly 50. The casing 30includes a generally oblong-shaped tank portion which is closed atopposed ends by respective walls 32 and 33. The end wall 33 ispreferably detachably secured to the sidewalls (provided by the tank andidentifiedby reference numeral 34) and projects laterally beyond suchwalls for the purpose which will become apparent hereinafter. Aplurality of cooling fins project outwardly from the casing sidewall 34and consist of a plurality of channel members each having a plurality oftins 36 projecting outwardly from a web member 37. The members, eachconsisting of a web 37 and fins 36, may be extruded or rolled and arefrom a highly heat-conductive material. The webs 37 are disposed inspaced relation with respect tothe casing sidewall 34 (see FIG. 4) andadjacent elements are also disposed in spaced relation. The elements aresecured to the casing as, for example, by welding the upper and lowerends to the side walls of the casing. Since the end wall 33 projectslaterally beyond the side wall 34 of the casing, the cooling fins mayalso be secured thereto. Alternatively, the end wall 33 may terminateflush with the sidewall of the casing in which event spacer elements maybe utilized to interconnect the webs 37 and the sidewall 34.

The casings 20 and 30 each preferably consist of an aluminum or analuminum alloy or any other material of highly heat-conductivecharacteristics. Cooling fins may be provided on either of the casings20 or 30 and they may consist of separate elements, as previouslydescribed, or alternatively be formed integral with the side walls. Apair of bushing members 26 are secured to the top wall and a pair ofbushings 27 are secured to the bottom wall in each of the transformersillustrated and provide connections to the coils located within thecasing.

The core and coil assembly 50 consists of a coil portion 51 and a coreportion 52. The core portion 52 consists of a ribbon of highlymagnetizable material spirally wound flatwise around each of the legs ofthe generally rectangular-shaped coil 51. The magnetizable material ispreferably a silicon steel with grain orientation parallel to the lengthof the ribbon well known and commonly used in transfonners. The coilportion 51 of the core and coil assembly 50 consists of a primarywinding 53 sandwiched between a pair of secondary windings 54. Each ofthe primary and secondary coils consists of a plurality of turns ofconductor 55 encapsulated in a potting compound 56 of preferably ahigh-temperature resistant epoxy resin or some other potting compound,for example, phenolic resins. Y

The potting compound may be a resin such as an epoxy, polyester orsilicone type either filled or unfilled, or any other well-known typesselected to provide suitable characteristics such as temperature ofoperation and thereby class the transformer as to operation. Ahigh-temperature potting compound minimizes heat sinking and an epoxyfound suitable in No. 2258 Epoxy of Union Carbide with CIBAs No. 972hardener. Anhydride epoxy systems are deemed suitable. Numerousproposals have been made concerning various suitable encapsulants and inthis regard, attention is directed to Canadian Pat. Nos. 76l,60l and734,998 issued, respectively, June 20, 1967 and May 24, 1966.

The encapsulant 56 has a smooth external surface 57 covered with a thinsemiconductive coating 58 of, for example, metal. The coating 58, forexample, may be a resin filled with carbon black and/or metal powder, orit may be a metal surface. The resin-filled material may be applied bypainting, spraying or the like, or the metal may be applied as, forexample, by metal flame spray. It is most important that the surface 57be. extremely smooth and the conductivity low enough so as not toprovide a short circuit turn for the coils.

The primary and secondary coils may be rectangular in cross section, asillustrated in FIG. 6, or alternatively, only the primary winding 53 maybe rectangular in cross section, as illustrated in FIG. 9, having a pairof opposed flat faces 59 and 60 disposed adjacent a flat face 61 ofrespective ones of the pair of secondary coils 54. The remainingexternal surfaces of the coils 53 and 54 are such that the assembledcoils define a substantially circular outline. The coil portion 51 mayconsist of two or more coils assembled in side-by-side relation althoughonly three coils have been illustrated in the drawings.

Each coil element, that is, the primary 53 and secondaries 54 arephysically in the form of closed loops as illustrated in FIG. 5. Eachcoil element further includes a pair of posts 62 projecting outwardlytherefrom and in selected spaced relationship with respect to oneanother. The posts 62 are formed from the encapsulant and include aferrule 63 (see FIG. ll) embedded therein. The ferrule 63 serves toconnect a terminal 64 to the terminal end of the conductor 55. Theferrule 63 has a bore 65 extending inwardly from one end thereofreceiving an end portion of the conductor 55 and may be crimped orotherwise deformed to clampingly engage the conductor. Alternatively oradditionally, a set screw may be used which is threaded into the ferruleand projects into the bore 65 for engagement with the conductor. Theopposite end of the ferrule has a threaded bore 66 threadingly toreceive a terminal post 64. The ferrule 63 and conductor 55 may be thesame material or alternatively, dissimilar materials. For example,conductor 55 may be aluminum and the ferrule 63 may be aluminum orcopper or brass. The ferrule and conductor are embedded in theencapsulant 56 and, accordingly, interaction of dissimilar metals isminimized because of being unexposed to the atmosphere.

The posts 62 each have a tapered conical recess 67 in the end thereoffor receiving a correspondingly shaped portion of a bushing 26 (see FIG.2 where there are illustrated bushings 26 and 27). Each of the bushings26 and 27 have a tapered end portion 68 which projects into the conicalrecess 67 and has an enlarged outer end portion 69 which overlies theremaining portion of the post 62. The bushings 26 and 27 may be ceramic,epoxy resins, phenolic resins or the like and have a central bore forreceiving the terminal post 64. The bushing 26 is held in assembledrelation by a lock nut N1 threaded onto the terminal 64 and a furthernut N2 may be provided for connecting conductors to the terminal. Whenassembled, the bushings 26 and 27 have the sloped tapered ends 68thereof in pressural engagement with the sloped sidewalls of the recess67 preventing entry of foreign matter into the connection of theterminal post to the ferrule. The connectors accordingly are projectedfrom the elements and, if desired, suitable sealing materials may beutilized between the bushing 26 and the terminal post to completelyseparate the connection of terminal 64 to the ferrule 63 from air andthus avoid deterioration which might otherwise be caused.

In the transformer illustrated in FIG. 2, the enlarged portion 69 of thebushing 26 engages the outer face of the casing top wall 24 and theopposite side of the wall 24 engages the pair of posts 62. Similarly,the downwardly directed posts 62 of the coil assembly engage the casingbottom wall 25 supporting the core and coil assembly in the casing andthe bushings 27 engage the lower face of the bottom wall. The bushings26 and 27 accordingly retain the core and coil assembly in assembledrelation with respect to the casing which surrounds the core and coilassembly. In the arrangement illustrated in FIG. 2, bushings 26 with theterminals thereon project upwardly above the casing and it will be notedthat the casingrsidewalls project downwardly below the bottom bushings27 and the terminals associated therewith. The lower terminals,accordingly, are protected'from atmosphere and a further cover plate maybe secured to the casing providing an enclosed area for the lowerterminals.

The coil portion of the transformer is illustrated in FIGS. 6 to 9inclusive and, as previously mentioned, there is a primary coil locatedintermediate a pair of secondary coils. Each of the primary andsecondary coils are discrete separate elements consisting of conductorsencapsulated in a potting compound having a smooth outer surface whichpreferably is covered with a semiconductive coating. The secondariesneed not be coated but it is preferable that at least the primary orhigh voltage winding be coated. The coils 53 and 54 are disposed inside-by-side relation as illustrated in close abutting relation, and thecore for the transformer consists of a ribbon of magnetizable materialwound flatwise around each of the four legs of the rectangularly shapedcoils. The ribbon may be wound tightly to hold the primary and secondarycoils in an assembled relation. Alternatively, the spirally wound ribbonmaterial may be replaced by flat sheet stock consisting of arrangedpairs of oppositely directed U-shaped elements suitably joined as iscommonly known in the transfonner art (see, for example, Canadian Pat.No. 52!,487 issued Feb. 7, 1956). In a transformer of this type arrangedwith discrete coil elements, one coil may be readily replaced whenburned out merely by removing the core material and substituting anoperative coil for the unserviceable one.

In order to facilitate dissipating heat from the transformer illustratedin FIGS. 1 and 2, heat sinks 70 are provided and consist of highlyheat-conductive metal fins directly engageable with the transformercasing 20. The fins 70 may be welded to the casing or clampingly engagedbetween the casing flanges 23, as illustrated in FIG. 1. There is a pairof heat sinks 70 located at each of the four corners of the rectangularcore and coil assembly in the transformer illustrated in FIG. 2. Eachheat sink 70 includes a flat portion 71 disposed intermediate adjacentcoils 53 and 54 with a portion 72 projecting inwardly of a core 52 woundon one leg and a further portion 73 projecting inwardly of the core 52located on a leg adjacent thereto. The portions 72 and 73 of the heatsinks are effectively, arms extending at right angles to one another andare clampingly engaged between the adjacently disposed coils. Each heatsink 70 includes an angular portion 74 merging into an outer end portion75 located between the casing flanges 23. The heat sinks 70 arepreferably aluminum or an aluminum alloy or some other highlyheat-conductive material and serve to dissipate heat from the core andcoil assembly. The heat sinks further serve the purpose of retaining thecore and coil assembly in a selected location relative to the casing.

Each of the coils 53 and 54 may be formed in a manner as illustrated inFIGS. 12 to 14 inclusive. It is important to have the external surfaceof the encapsulant of each coil free from depressions, i.e. a relativelysmooth surface and in order to accomplish this, the coil unit ispreferably formed in a mold. Referring to FIG. 12, there is illustrateda coil 54 in a fonning mold 80. The mold consists of a two-part backingmember 81 and a cover member 82 held in assembled relation by aplurality of U-shaped clips or clamp members 83. The member 81 may be aunitary member but in the preferred form, consists of a pair of members84 and 85 which may be readily assembled and disassembled. The member 84is generally T-shaped in cross section having a peripheral concavegroove 86 in one face thereof surrounding a generally flat planarportion 87. The member 81 terminates in an outer peripheral edge 88tapered inwardly in a direction outwardly from the mold. The purpose ofthis will become apparent hereinafter.

The member 85 is elTectively annular in shape, having a substantiallyflat bearing surface 89 engageable with an adjacent flat face of thecover member 82. The member 85 has a peripheral grooved or recessedportion 90 contiguous with the groove 86 in the member 84. The groovedportion 90 merges into a further portion 91 which is complementary tothe shape of the peripheral surface or edge 88 of the member 81. Theremaining portion of the member 85 may be of any configuration and, forexample, may include a peripheral flange 92 for the purpose offacilitating interconnecting the members 81 and 82. The members 84 and85 may be readily assembled and disassembled merely by fitting themember 84 into the member 85, positioning being facilitated bycomplementary shaped abutting surfaces 88 and 91 on the respectivemembers. In assembled relation, the surface of the groove 86 iscontiguous, as previously mentioned, with the surface of the groove 90so as to provide a smooth molding surface for the coil 54 located in themolding chamber. The clips 83 may be substantially U-shaped, in crosssection, members retained by frictional engagement on the cover 82 andflange 92thereby retaining the members 81 and 82 in assembled relation.Adjustable clips may be utilized or, if desired, the cover 82 may befastened by means of studs or the like to the member 85 and/or 84.

The member 84, as previously mentioned, is readily removable from theannular outer member 85 and the purpose of such arrangement is so thatthe member 84 may be utilized as a winding form or mandril. In thisregard, the coil consists of a plurality of turns of conductor 55 woundinto a closed loop. Referring to FIG. 13, the conductor 55 may consistof a conductor 700 drawn off a spool 701 pivotally mounted on a shaft702 by a winding unit 703. The conductor may be either a bare wire or aninsulated wire and in either event, an adhesive material 705 is appliedto at least selected portions for holding a spacer on the conductor, thepurpose of which will become apparent hereinafter. The adhesive ispreferably a silicone type and may be applied by rollers, brushes or thelike applicators, and either as a continuous film or alternatively, instrips in which case they would normally extend longitudinally along theconductor. In FIG. 13, the conductor 700 is illustrated as being drawnthrough a bath of adhesive material 705 contained within a tank 706.Alternatively, the conductor may be insulated by a coating which may besuitably treated as, for example, by the application of heat, solventsor the like to provide a tacky surface in which case the insulation ofthe conductor performs the dual function of being an, insulator andselectively an adhesive surface. The tacky surface or adhesive is forthe purpose of retaining a spacer element on the conductor.

Downstream from the adhesive-applying station, the conductor with theadhesive thereon is indicated generally by the reference numeral 715.Filament glass 710 in rope form is drawn off a bobbin 711 mounted on ashaft 712 to rotate about a substantially horizontal axis. The rope formof filament glass is drawn off the bobbin 711 by a winding arm 713mounted to rotate about the longitudinal axis of the conductor. Thewinding arm consists of a member directed outwardly from the axis of theconductor and has at least one arm adjacent the free end thereofextending parallel to the length of the conductor. The filament glass isdrawn off the bobbin through a combing element 714 to form the strandsinto a flat ribbon and such flat ribbon is spirally wound around theconductor by the winding arm as the wire is moved horizontally to theright as viewed in FIG. 13. The adhesive-covered conductor 715, with thefilament glass thereon, is wound onto a winding mandril, preferablyunder tension so as to place the adjacent windings of the coil in tightintimate contact. The wind ing mandril rotates about the axis of adriven shaft 720 to which is secured a plate 721. The plate 721 includesa plurality of apertures 722 through which studs may pass and bethreaded into the member 84 (FIG. 12) with the face 87 thereof inabutting relation with the plate 721. The latter plate may extendlaterally beyond the member 84 a selected amount and together provideeffectively a reel for winding a plurality of turns of the conductorinto a closed loop coil. After the conductor has been wound onto themember 84,

which effectively is a winding mandrel, the latter is removed from theplate 721 and inserted into the member 85 whereafter the cover 82 isattached by the clips 83. The entire assembly, generally designated inFIG. 12 by reference numeral 80, is then placed in a vacuum chamber 1200and the space confining the coil 54 is connected by a conduit 1101 to asupply of potting compound 1103. The potting compound, or encapsulant asit may be referred to, may be a resin such as an epoxy, silicone,polyesters, e.g. Vibrin or Permasil or the like, either filled orunfilled, or any type selected to provide suitable range of temperatureoperation and thereby class the transformer as to operation.

A bleeder conduit 1102 is connected to the chamber containing the coil54 and a control valve 1104 located in the bleeder line 1102 may beselectively opened and closed to control filling the chamber containingthe coil 54 with the potting compound 1103. The vacuum chamber 1200 isevacu ated to selected negative pressures by a vacuum pump generallydesignated 1300. After the chamber containing the coil has beencompletely filled with the potting compound, the the potting compound isthen cured and when using a thermal setting resin as the pottingcompound, the coil may be energized to provide the necessary heat toaccomplish the curing. The coil assembly 54 in the mold is then removedfrom the vacuum chamber and the coil 54 removed from themold.Theencapsulated coil is then completely covered with a metallized surfaceor semiconductor. The coating, for example, may consist of a resinfilled with carbon black and may be applied by spraying or,alternatively, it may consistof a resin filled with a metal powder andlikewise applied by spraying. The coating alternatively may be metalapplied by flame spraying so as to deposit discrete particles of metalin a continuous layer.

The cross-sectional shape of the encapsulant is determined by the shapeof the chamber in the mold 80. The coils are ap propriately shaped as,for example, that illustrated in FIG. 9 where three coil assemblies,arranged side-by-side in close abutting relation, present asubstantially circular outline or alternatively, substantially square asshown in FIG. 7. Coils assembled side-by-side are then embraced atselected areas by core material 52 which, as previously mentioned, is aribbon of silicon steel or the like spirally wound flatwise around theassembled coils to embrace the same.

With regards to disposing the coil assembly side-by-side, discrete coilelements, that is, individual primaries and secondaries as illustratedin FIG. 8, permit stacking a series of coil elements to vary the size ofthe transformer. For example, two primary coils may be locatedintermediate two secondaries, or alternatively, primary and secondarycoils may be arranged in alternate relation and the entire assemblyembraced by core material. In stacking, it is preferable to maintain allof the coils physically symmetrical and when stacked, the coils may besuitably interconnected electrically, for example, all of the primarycoils may be connected in parallel and likewise all of the secondarycoils may be connected in parallel.

From the foregoing, it is seen that the metallized film which completelycovers each coil segment separates one winding from the other. Themetallized surface provides a transformer which is substantially freefrom corona and helps to increase the basic insulation level of the coreand coil assembly. The use of an encapsulant which is molded to arelatively smooth outer surface cuts down or eliminates spiking, thatis, surfaces which project inwardly toward the coil and thereby reducesflash inducing edges or points.

We claim: 1. Inductive device including a core and coil assemblycomprising at least two closed loop coil elements disposed with exteriorclosed-loop surfaces in side-by-side contiguous relationship, each ofsuch coil elements comprising a plurality of electrically insulatedturns in an integral encapsulation and at least one body of magnetizablematerial embracing in common a selected portion of the side-by-sidecoils and, casing means enclosing the core and coil assembly,

the coil encapsulation including integral projection means extendingfrom the coil elements to the casing means so as to support the coilelements within the casing means.

2. The structure of claim 1 further including a semiconductive filmcovering the external surface of at least one of the integralencapsulations.

3. The structure of claim 1 including at least one heat conductivemember having a portion interposed between the contiguous coils.

4. The structure of claim 3 wherein the heat conductive member isextended to engage the casing.

5. The inductive device of claim 1 in which the plurality of electricalturns of an electrifircoil terminate in a bushing which is unitary withthe encapsulation.

6. A coil assembly for use in an encased inductive device comprising acasing and a plurality of electrical turns in an integral encapsulantincluding post means integrally formed of such encapsulant andsupporting the integral encapsulant in the casing.

7. The structure of claim 6 in which the post means include bushingssecured thereto and which project outwardly from the casing.

II I I I

1. Inductive device including a core and coil assembly comprising atleast two closed loop coil elements disposed with exterior closed-loopsurfaces in side-by-side contiguous relationship, each of such coilelements comprising a plurality of electrically insulated turns in anintegral encapsulation and at least one body of magnetizable materialembracing in common a selected portion of the side-by-side coils and,casing means enclosing the core and coil assembly, the coilencapsulation including integral projection means extending from thecoil elements to the casing means so as to support the coil elementswithin the casing means.
 2. The structure of claim 1 further including asemiconductive film covering the external surface of at least one of theintegral encapsulations.
 3. The stRucture of claim 1 including at leastone heat conductive member having a portion interposed between thecontiguous coils.
 4. The structure of claim 3 wherein the heatconductive member is extended to engage the casing.
 5. The inductivedevice of claim 1 in which the plurality of electrical turns of anelectrical coil terminate in a bushing which is unitary with theencapsulation.
 6. A coil assembly for use in an encased inductive devicecomprising a casing and a plurality of electrical turns in an integralencapsulant including post means integrally formed of such encapsulantand supporting the integral encapsulant in the casing.
 7. The structureof claim 6 in which the post means include bushings secured thereto andwhich project outwardly from the casing.